1. Technical Field
The present disclosure relates to a NFC antenna, in particular, to a NFC antenna reducing interferences affected by metal elements.
2. Description of Related Art
A conventional near field communication (NFC) antenna can be formed by ring type conductors and disposed surrounding a screen and a keyboard of an electronic device, such that the electronic device can communicate with other electronic devices by using a point-to-point contactless communication.
For example, refer to FIG. 1A, which shows a schematic diagram of the conventional NFC antenna. The conventional NFC antenna 1 includes a radiating portion 11 and a dielectric layer 10. The radiating portion 11 is disposed on one side of the dielectric layer 10. The radiating portion 11 includes a signal input terminal 111, a conducting wire 112 and a signal output terminal 113. The conducting wire 112 is electrically connected to the signal input terminal 111 and the signal output terminal 113. The conducting wire 112 surrounds an axis core 12 with multiple circles and formed a spiral structure. The signal input terminal 111 is not electrically connected to the signal output terminal 113.
Furthermore, referring to FIG. 1B, which shows an equivalent circuit of the conventional NFC antenna. In FIG. 1B, the equivalent circuit of the conventional NFC antenna 1 is mainly formed by an inductor Lx. However, the inductor Lx is not an ideal inductor, such that the conventional NFC antenna 1 exists also as a parasitic capacitor Cx and a parasitic resistor Rx. Hence, when the electronic device disposed with the conventional NFC antenna 1 communicates with a reader disposed with the conventional NFC antenna 1, if the conventional NFC antenna 1 has a low quality factor (Q factor) and the conventional NFC antenna 1 of the reader is affected by metal elements surrounding the reader, both of the quality factor of the conventional NFC antenna 1 and a transmission distance between the electronic device and the reader are decreased.